Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Genet Med ; 2019 Nov 08.
Artigo em Inglês | MEDLINE | ID: mdl-31700164

RESUMO

PURPOSE: Most classical aniridia is caused by PAX6 haploinsufficiency. PAX6 missense variants can be hypomorphic or mimic haploinsufficiency. We hypothesized that missense variants also cause previously undescribed disease by altering the affinity and/or specificity of PAX6 genomic interactions. METHODS: We screened PAX6 in 372 individuals with bilateral microphthalmia, anophthalmia, or coloboma (MAC) from the Medical Research Council Human Genetics Unit eye malformation cohort (HGUeye) and reviewed data from the Deciphering Developmental Disorders study. We performed cluster analysis on PAX6-associated ocular phenotypes by variant type and molecular modeling of the structural impact of 86 different PAX6 causative missense variants. RESULTS: Eight different PAX6 missense variants were identified in 17 individuals (15 families) with MAC, accounting for 4% (15/372) of our cohort. Seven altered the paired domain (p.[Arg26Gln]x1, p.[Gly36Val]x1, p.[Arg38Trp]x2, p.[Arg38Gln]x1, p.[Gly51Arg]x2, p.[Ser54Arg]x2, p.[Asn124Lys]x5) and one the homeodomain (p.[Asn260Tyr]x1). p.Ser54Arg and p.Asn124Lys were exclusively associated with severe bilateral microphthalmia. MAC-associated variants were predicted to alter but not ablate DNA interaction, consistent with the electrophoretic mobility shifts observed using mutant paired domains with well-characterized PAX6-binding sites. We found no strong evidence for novel PAX6-associated extraocular disease. CONCLUSION: Altering the affinity and specificity of PAX6-binding genome-wide provides a plausible mechanism for the worse-than-null effects of MAC-associated missense variants.

2.
Am J Med Genet A ; 176(9): 1950-1955, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30144375

RESUMO

Transient receptor potential vanilloid 6 (TRPV6) functions in tetramer form for calcium transport. Until now, TRPV6 has not been linked with skeletal development disorders. An infant with antenatal onset thoracic insufficiency required significant ventilatory support. Skeletal survey showed generalized marked undermineralization, hypoplastic fractured ribs, metaphyseal fractures, and extensive periosteal reaction along femoral, tibial, and humeral diaphyses. Parathyroid hormone (PTH) elevation (53.4-101 pmol/L) initially suggested PTH signaling disorders. Progressively, biochemical normalization with radiological mineralization suggested recovery from in utero pathophysiology. Genomic testing was undertaken and in silico protein modeling of variants. No abnormalities in antenatal CGH array or UPD14 testing. Postnatal molecular genetic analysis found no causative variants in CASR, GNA11, APS21, or a 336 gene skeletal dysplasia panel investigated by whole exome sequencing. Trio exome analysis identified compound heterozygous TRPV6 likely pathogenic variants: novel maternally inherited missense variant, c.1978G > C p.(Gly660Arg), and paternally inherited nonsense variant, c.1528C > T p.(Arg510Ter), confirming recessive inheritance. p.(Gly660Arg) generates a large side chain protruding from the C-terminal hook into the interface with the adjacent TRPV6 subunit. In silico protein modeling suggests steric clashes between interface residues, decreased C-terminal hook, and TRPV6 tetramer stability. The p.(Gly660Arg) variant is predicted to result in profound loss of TRPV6 activity. This first case of a novel dysplasia features severe but improving perinatal abnormalities. The TRPV6 compound heterozygous variants appear likely to interfere with fetoplacental calcium transfer crucial for in utero skeletal development. Astute clinical interpretation of evolving perinatal abnormalities remains valuable in complex calcium and bone pathophysiology and informs exome sequencing interpretation.

3.
Am J Med Genet A ; 176(5): 1108-1114, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29383814

RESUMO

Variants in the Protein Kinase CK2 alpha subunit, encoding the CSNK2A1 gene, have previously been reported in children with an intellectual disability and dysmorphic facial features syndrome: now termed the Okur-Chung neurodevelopmental syndrome. More recently, through trio-based exome sequencing undertaken by the Deciphering Developmental Disorders Study (DDD study), a further 11 children with de novo CSNK2A1 variants have been identified. We have undertaken detailed phenotyping of these patients. Consistent with previously reported patients, patients in this series had apparent intellectual disability, swallowing difficulties, and hypotonia. While there are some shared facial characteristics, the gestalt is neither consistent nor readily recognized. Congenital heart abnormalities were identified in nearly 30% of the patients, representing a newly recognized CSNK2A1 clinical association. Based upon the clinical findings from this study and the previously reported patients, we suggest an initial approach to the management of patients with this recently described intellectual disability syndrome.

4.
Prenat Diagn ; 38(1): 33-43, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29096039

RESUMO

OBJECTIVE: Rare genetic disorders resulting in prenatal or neonatal death are genetically heterogeneous, but testing is often limited by the availability of fetal DNA, leaving couples without a potential prenatal test for future pregnancies. We describe our novel strategy of exome sequencing parental DNA samples to diagnose recessive monogenic disorders in an audit of the first 50 couples referred. METHOD: Exome sequencing was carried out in a consecutive series of 50 couples who had 1 or more pregnancies affected with a lethal or prenatal-onset disorder. In all cases, there was insufficient DNA for exome sequencing of the affected fetus. Heterozygous rare variants (MAF < 0.001) in the same gene in both parents were selected for analysis. Likely, disease-causing variants were tested in fetal DNA to confirm co-segregation. RESULTS: Parental exome analysis identified heterozygous pathogenic (or likely pathogenic) variants in 24 different genes in 26/50 couples (52%). Where 2 or more fetuses were affected, a genetic diagnosis was obtained in 18/29 cases (62%). In most cases, the clinical features were typical of the disorder, but in others, they result from a hypomorphic variant or represent the most severe form of a variable phenotypic spectrum. CONCLUSION: We conclude that exome sequencing of parental samples is a powerful strategy with high clinical utility for the genetic diagnosis of lethal or prenatal-onset recessive disorders. © 2017 The Authors Prenatal Diagnosis published by John Wiley & Sons Ltd.


Assuntos
Anormalidades Congênitas/genética , Doenças Genéticas Inatas/diagnóstico , Pais , Diagnóstico Pré-Natal/métodos , Sequenciamento Completo do Exoma , Feminino , Genes Recessivos , Humanos , Masculino , Gravidez
5.
J Mol Med (Berl) ; 93(7): 773-82, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25686753

RESUMO

UNLABELLED: Filamin A, the filamentous protein encoded by the X-linked gene FLNA, cross-links cytoskeletal actin into three-dimensional networks, facilitating its role as a signalling scaffold and a mechanosensor of extrinsic shear forces. Central to these functions is the ability of FLNA to form V-shaped homodimers through its C-terminal located filamin repeat 24. Additionally, many proteins that interact with FLNA have a binding site that includes the C-terminus of the protein. Here, a cohort of patients with mutations affecting this region of the protein is studied, with particular emphasis on the phenotype of male hemizygotes. Seven unrelated families are reported, with five exhibiting a typical female presentation of periventricular heterotopia (PH), a neuronal migration disorder typically caused by loss-of-function mutations in FLNA. One male presents with widespread PH consistent with previous male phenotypes attributable to hypomorphic mutations in FLNA. In stark contrast, two brothers are described with a mild PH presentation, due to a missense mutation (p.Gly2593Glu) inserting a large negatively charged amino acid into the hydrophobic dimerisation interface of FLNA. Co-immunoprecipitation, in vitro cross-linking studies and gel filtration chromatography all demonstrated that homodimerisation of isolated FLNA repeat 24 is abolished by this p.Gly2593Glu substitution but that extended FLNA(Gly2593Glu) repeat 16-24 constructs exhibit dimerisation. These observations imply that other interactions apart from those mediated by the canonical repeat 24 dimerisation interface contribute to FLNA homodimerisation and that mutations affecting this region of the protein can have broad phenotypic effects. KEY MESSAGES: • Mutations in the X-linked gene FLNA cause a spectrum of syndromes. • Genotype-phenotype correlations are emerging but still remain unclear. • C-term mutations can confer male lethality, survival or connective tissue defects. • Mutations leading to the latter affect filamin dimerisation. • This deficit is compensated for by remotely acting domains elsewhere in FLNA.


Assuntos
Filaminas/genética , Heterotopia Nodular Periventricular/genética , Multimerização Proteica/genética , Sequência de Aminoácidos , Movimento Celular/genética , Feminino , Fibroblastos , Estudos de Associação Genética , Humanos , Masculino , Dados de Sequência Molecular , Mutação de Sentido Incorreto/genética , Fenótipo , Estrutura Terciária de Proteína
6.
J Med Genet ; 50(11): 765-71, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23922384

RESUMO

BACKGROUND: Stickler syndromes types 1, 2 and 3 are usually dominant disorders caused by mutations in the genes COL2A1, COL11A1 and COL11A2 that encode the fibrillar collagens types II and XI present in cartilage and vitreous. Rare recessive forms of Stickler syndrome exist that are due to mutations in genes encoding type IX collagen (COL9A1 type 4 Stickler syndrome and COL9A2 type 5 Stickler syndrome). Recently, recessive mutations in the COL11A1 gene have been demonstrated to result in fibrochondrogenesis, a much more severe skeletal dysplasia, which is often lethal. Here we demonstrate that some mutations in COL11A1 are recessive, modified by alternative splicing and result in type 2 Stickler syndrome rather than fibrochondrogenesis. METHODS: Patients referred to the national Stickler syndrome diagnostic service for England, UK were assessed clinically and subsequently sequenced for mutations in COL11A1. Additional in silico and functional studies to assess the effect of sequence variants on pre-mRNA processing and collagen structure were performed. RESULTS: In three different families, heterozygous COL11A1 biallelic null, null/missense or silent/missense mutations, were found. They resulted in a recessive form of type 2 Stickler syndrome characterised by particularly profound hearing loss and are clinically distinct from the recessive types 4 and 5 variants of Stickler syndrome. One mutant allele in each family is capable of synthesising a normal α1(XI) procollagen molecule, via variable pre-mRNA processing. CONCLUSION: This new variant has important implications for molecular diagnosis and counselling families with type 2 Stickler syndrome.


Assuntos
Processamento Alternativo , Colágeno Tipo XI/genética , Doenças do Tecido Conjuntivo/genética , Perda Auditiva/genética , Mutação , Descolamento do Vítreo/genética , Adulto , Sequência de Aminoácidos , Pré-Escolar , Colágeno Tipo XI/deficiência , Feminino , Humanos , Lactente , Masculino , Dados de Sequência Molecular , Linhagem
7.
Am J Med Genet A ; 161A(8): 2027-9, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23813970

RESUMO

Medulloblastoma is the commonest brain tumor in childhood and in a minority of patients is associated with an underlying genetic disorder such as Gorlin syndrome or familial adenomatous polyposis. Increased susceptibility to certain tumors, including neuroblastoma and some hematological malignancies, is recognized in disorders caused by mutations in genes encoding components of the RAS signaling pathway which include Noonan syndrome, Noonan syndrome with multiple lentigines (NSML; formerly called LEOPARD syndrome), Costello syndrome, Cardiofaciocutaneous syndrome, Legius syndrome, and Neurofibromatosis type 1 (NF1), collectively termed RASopathies. Although an association between medulloblastoma and NF1 has been reported, this tumor has not previously been reported in other RASopathies. We present a patient with NSML caused by the recurrent PTPN11 mutation c.1403C > T (p.Thr468Met) in whom medulloblastoma was diagnosed at age 10 years. Medulloblastoma could therefore be part of the tumor spectrum associated with this disorder.


Assuntos
Síndrome LEOPARD/genética , Meduloblastoma/etiologia , Mutação/genética , Proteína Tirosina Fosfatase não Receptora Tipo 11/genética , Adulto , DNA/análise , DNA/genética , Humanos , Síndrome LEOPARD/complicações , Masculino , Meduloblastoma/patologia , Pessoa de Meia-Idade , Fenótipo , Reação em Cadeia da Polimerase , Adulto Jovem
8.
Eur J Hum Genet ; 20(4): 381-8, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22126750

RESUMO

MLL2 mutations are detected in 55 to 80% of patients with Kabuki syndrome (KS). In 20 to 45% patients with KS, the genetic basis remains unknown, suggesting possible genetic heterogeneity. Here, we present the largest yet reported cohort of 116 patients with KS. We identified MLL2 variants in 74 patients, of which 47 are novel and a majority are truncating. We show that pathogenic missense mutations were commonly located in exon 48. We undertook a systematic facial KS morphology study of patients with KS at our regional dysmorphology meeting. Our data suggest that nearly all patients with typical KS facial features have pathogenic MLL2 mutations, although KS can be phenotypically variable. Furthermore, we show that MLL2 mutation-positive KS patients are more likely to have feeding problems, kidney anomalies, early breast bud development, joint dislocations and palatal malformations in comparison with MLL2 mutation-negative patients. Our work expands the mutation spectrum of MLL2 that may help in better understanding of this molecule, which is important in gene expression, epigenetic control of active chromatin states, embryonic development and cancer. Our analyses of the phenotype indicates that MLL2 mutation-positive and -negative patients differ systematically, and genetic heterogeneity of KS is not as extensive as previously suggested. Moreover, phenotypic variability of KS suggests that MLL2 testing should be considered even in atypical patients.


Assuntos
Anormalidades Múltiplas/genética , Proteínas de Ligação a DNA/genética , Heterogeneidade Genética , Doenças Hematológicas/genética , Mutação , Proteínas de Neoplasias/genética , Fenótipo , Doenças Vestibulares/genética , Estudos de Coortes , Face/anormalidades , Feminino , Humanos , Análise de Sequência de DNA
9.
Cilia ; 1(1): 18, 2012 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-23351400

RESUMO

BACKGROUND: Meckel-Gruber syndrome (MKS) is an autosomal recessive lethal condition that is a ciliopathy. MKS has marked phenotypic variability and genetic heterogeneity, with mutations in nine genes identified as causative to date. METHODS: Families diagnosed with Meckel-Gruber syndrome were recruited for research studies following informed consent. DNA samples were analyzed by microsatellite genotyping and direct Sanger sequencing. RESULTS: We now report the genetic analyses of 87 individuals from 49 consanguineous and 19 non-consanguineous families in an unselected cohort with reported MKS, or an associated severe ciliopathy in a kindred. Linkage and/or direct sequencing were prioritized for seven MKS genes (MKS1, TMEM216, TMEM67/MKS3, RPGRIP1L, CC2D2A, CEP290 and TMEM237) selected on the basis of reported frequency of mutations or ease of analysis. We have identified biallelic mutations in 39 individuals, of which 13 mutations are novel and previously unreported. We also confirm general genotype-phenotype correlations. CONCLUSIONS: TMEM67 was the most frequently mutated gene in this cohort, and we confirm two founder splice-site mutations (c.1546 + 1 G > A and c.870-2A > G) in families of Pakistani ethnic origin. In these families, we have also identified two separate founder mutations for RPGRIP1L (c. 1945 C > T p.R649X) and CC2D2A (c. 3540delA p.R1180SfsX6). Two missense mutations in TMEM67 (c. 755 T > C p.M252T, and c. 1392 C > T p.R441C) are also probable founder mutations. These findings will contribute to improved genetic diagnosis and carrier testing for affected families, and imply the existence of further genetic heterogeneity in this syndrome.

10.
Cardiol Young ; 20(5): 580-3, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20663266

RESUMO

We report the case of a young woman with a troponin mutation of C to T nucleotide substitution in exon 17 of troponin 2 (TNNT2; c.868C.T; p.Arg288Cys) leading to hypertrophic obstructive cardiomyopathy. Following surgical resection of the outflow obstruction, she had near-complete resolution of her asymmetric left ventricular hypertrophy, such that cardiomyopathy could no longer be diagnosed on echocardiographic grounds. We believe that this unusual case shows important aspects relating to the interplay between genetic and environmental mechanisms and the overlap in the phenotypic spectrum between primary subaortic stenosis and obstructive hypertrophic cardiomyopathy.


Assuntos
Procedimentos Cirúrgicos Cardíacos/métodos , Cardiomiopatia Hipertrófica/complicações , Hipertrofia Ventricular Esquerda/etiologia , Recuperação de Função Fisiológica , Troponina/sangue , Função Ventricular Esquerda/fisiologia , Obstrução do Fluxo Ventricular Externo/cirurgia , Adulto , Cardiomiopatia Hipertrófica/sangue , Cardiomiopatia Hipertrófica/cirurgia , Feminino , Seguimentos , Humanos , Hipertrofia Ventricular Esquerda/diagnóstico , Hipertrofia Ventricular Esquerda/fisiopatologia , Gravidez , Complicações Cardiovasculares na Gravidez , Obstrução do Fluxo Ventricular Externo/diagnóstico , Obstrução do Fluxo Ventricular Externo/etiologia
11.
Eur J Hum Genet ; 18(6): 648-55, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20104244

RESUMO

This study was an investigation of 79 patients referred to the Wessex Regional Genetics Laboratory with suspected Russell-Silver Syndrome or unexplained short stature/intra uterine growth restriction, warranting genetic investigation. Methylation status was analysed at target sequences within eleven imprinted loci (PLAGL1, IGF2R, PEG10, MEST1, GRB10, KCNQ1OT1, H19, IGF2P0, DLK1, PEG3, NESPAS). Thirty seven percent (37%) (29 of 79) of samples were shown to have a methylation abnormality. The commonest finding was a loss of methylation at H19 (23 of 29), as previously reported in Russell-Silver Syndrome. In addition, four of these patients had methylation anomalies at other loci, of whom two showed hypomethylation of multiple imprinted loci, and two showed a complete gain of methylation at IGF2R. This latter finding was also present in five other patients who did not have demonstrable changes at H19. In total, 7 of 79 patients showed a gain of methylation at IGF2R and this was significantly different from a normal control population of 267 individuals (P=0.002). This study in patients with growth restriction shows the importance of widening the epigenetic investigation to include multiple imprinted loci and highlights potential involvement of the IGF2R locus.


Assuntos
Metilação de DNA/genética , Retardo do Crescimento Fetal/genética , Loci Gênicos , Impressão Genômica , Transtornos do Crescimento/genética , Criança , Pré-Escolar , Estudos de Coortes , Deficiências do Desenvolvimento/genética , Epigênese Genética , Feminino , Loci Gênicos/genética , Impressão Genômica/fisiologia , Humanos , Recém-Nascido , Gravidez , RNA Longo não Codificante , RNA não Traduzido/genética , Receptor IGF Tipo 2/genética , Análise de Sequência de DNA , Síndrome de Silver-Russell/genética
12.
Mol Vis ; 14: 118-24, 2008 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-18253096

RESUMO

PURPOSE: Pseudoxanthoma elasticum (PXE) is an autosomal recessive disorder of connective tissue, affecting the retina, the skin, and the cardiovascular system. PXE is caused by mutations in ABCC6. Up to now, the literature reports that there are 180 different ABCC6 mutations in PXE. The purpose of this paper is to report eight novel mutations in ABCC6 and to update the spectrum and frequency of ABCC6 mutations in PXE patients. METHODS: Eye, skin, and DNA examinations were performed using standard methodologies. We newly investigated the gene in 90 probands by denaturing high-performance liquid chromatography (dHPLC) and direct sequencing. We examined a total of 166 probands. RESULTS: Eight novel ABCC6 mutations (c.1685T>C, p.Met562Thr; c.2477T>C, p.Leu826Pro; c.2891G>C, p.Arg964Pro; c.3207C>A, p.Tyr1069X; c.3364delT, p.Ser1122fs; c.3717T>G, p.Tyr1293X; c.3871G>A, p.Ala1291Thr; c.4306_4312del, p.Thr1436fs) were found in seven unrelated patients. Currently, our mutation detection score is at least one ABCC6 mutation in 87% of patients with a clinical diagnosis of PXE. CONCLUSIONS: Our results support that ABCC6 is the most important, and probably the only, causative gene of PXE. In total, 188 different ABCC6 mutations have now been reported in PXE in the literature.


Assuntos
Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Mutação , Pseudoxantoma Elástico/genética , Sequência de Aminoácidos , Sequência de Bases , Cromatografia Líquida de Alta Pressão/métodos , Sequência Conservada , Feminino , Deleção de Genes , Humanos , Masculino , Mutação de Sentido Incorreto , Pseudoxantoma Elástico/patologia , Retina/patologia , Pele/patologia
14.
Am J Med Genet A ; 128A(2): 179-84, 2004 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-15214013

RESUMO

Léri-Weill dyschondrosteosis (LWD) and Langer mesomelic dysplasia (LMD) are caused by mutations in the SHOX gene. LWD results from haploinsufficiency and is dominantly inherited, while the more severe LMD results from the homozygous loss of SHOX. We describe a family and fetus with two SHOX mutations. Several relatives carry an approximately 200 kb interstitial deletion that includes the whole SHOX gene. Their condition is mild, with no Madelung deformity, and was originally diagnosed as hypochondroplasia (HCH). This deletion was also transmitted to a female fetus. However, unlike her carrier relatives, the ultrasound scan of the fetus and subsequent autopsy were consistent with LMD. The fetus inherited an additional Xp deletion (Xpter-Xp22.12) that also included the SHOX gene from her chromosomally normal father. This represents a unique molecular condition for LMD: the fetus is a compound heterozygote with two independent deletions, one inherited and one arising from a de novo event.


Assuntos
Anormalidades Múltiplas/genética , Nanismo/genética , Proteínas de Homeodomínio/genética , Mutação , Fatores de Transcrição/genética , Anormalidades Múltiplas/diagnóstico , Adulto , Alelos , Autopsia , Condrócitos/metabolismo , Cromossomos Humanos X , Cosmídeos , Saúde da Família , Feminino , Feto/anormalidades , Deleção de Genes , Heterozigoto , Homozigoto , Humanos , Hibridização in Situ Fluorescente , Masculino , Modelos Genéticos , Anormalidades Musculoesqueléticas/genética , Osteocondrodisplasias/genética , Linhagem , Fenótipo , Reação em Cadeia da Polimerase , Gravidez , Diagnóstico Pré-Natal , Proteína de Homoeobox de Baixa Estatura
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA